Table 1.

Demographic characteristics (mean [standard deviation]) of the study samples at each biennial visit, where Visit 0 corresponds to the timepoint of the MCI diagnosis in the NC-MCI sample

	Visit -6		Visit -5		Visit -4		Visit -3		Visit -2		Visit -1		Visit 0
	NC-NC	NC-MCI	NC-NC	NC-MCI	NC-NC	NC-MCI	NC-NC	NC-MCI	NC-NC	NC-MCI	NC-NC	NC-MCI	NC-NC	NC-MCI
Sample size	21	2	48	8	49	14	52	18	58	25	60	27	60	27
Y prior	– 12.56	– 12.79	– 10.78	– 10.98	– 8.53	– 8.83	– 6.45	– 6.72	– 4.30	– 4.45	– 2.00	– 2.22	0	0
to MCI Dx	(0.43)	(0.29)	(0.63)	(0.43)	(0.40)	(0.39)	(0.47)	(0.64)	(0.49)	(0.57)	(0.25)	(0.51)	(0.00)	(0.00)
Age	65.71	66.50	67.73	68.13	70.02	69.21	72.25	71.17	74.33	73.72	76.67	75.96	78.67	78.11
	(4.24)	(0.71)	(4.22)	(4.76)	(4.25)	(4.49)	(4.16)	(5.69)	(3.97)	(4.84)	(3.87)	(4.56)	(3.88)	(4.60)
Education	12.43	11.50	12.75	12.50	12.78	11.93	12.79	12.50	12.93	12.92	12.77	12.96	12.77	12.96
	(2.58)	(0.71)	(2.72)	(2.00)	(2.70)	(2.62)	(2.72)	(2.77)	(2.89)	(3.01)	(2.97)	(3.28)	(2.97)	(3.28)
Gender (% w)	47.6	0.0	37.5	37.5	36.7	35.7	40.4	33.3	43.1	44.0	41.7	40.7	41.7	40.7
MMSE	29.24	29.00	29.10	29.00	29.10	28.86	29.25	28.56	29.02	28.96	28.70	28.63	28.83	27.92
	(1.00)	(0.00)	(0.95)	(0.76)	(0.90)	(1.17)	(0.84)	(1.20)	(1.21)	(1.02)	(1.17)	(1.08)	(1.25)	(1.38)

Visit 0 was defined as that visit at which the NC-MCI patients received a diagnosis of MCI. The last visit data from NC-NC participants were yoked to NC-MCI visit 0 such that groups were optimally matched according to demographic variables, and neuropsychological data were retrospectively modeled. NC-NC, cognitively healthy participants who remained healthy throughout the entire observation period; NC-MCI, initially healthy participants who progressed to MCI at Visit 0; Y, years; Dx, diagnosis; w, women; MMSE, Mini-Mental State Examination [30].